Replace SpdyNameValueBlock typedef with SpdyHeaderBlock.

Replace SpdyNameValueBlock typedef with SpdyHeaderBlock.

Replace SpdyNameValueBlock typedef with SpdyHeaderBlock. Use SpdyHeaderBlock typedef more widely. No behavior change intended.

This CL is preparation for replacing SpdyHeaderBlock with an ordered datatype. Using the typedef in every place that currently explicitly uses map<string,string> will make this easier.

Other cleanup: replacing NameValueBlock with HeaderBlock, as in every case this is being used to store headers.

This CL lands server change 98865397 by rjshade.

BUG=443287
Committed: https://crrev.com/1f79b119adb1926e21be8959c283b66a25c91fc1
Cr-Commit-Position: refs/heads/master@{#341101}

[Bence, 2015-07-29 19:37:35]

bnc@chromium.org changed reviewers:
+ rch@chromium.org

[Bence, 2015-07-29 19:37:35]

Ryan, PTAL.  Thanks.

[Ryan Hamilton, 2015-07-29 22:42:14]

lgtm

[Bence, 2015-07-30 10:53:36]

The CQ bit was checked by bnc@chromium.org

[commit-bot: I haz the power, 2015-07-30 10:53:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1263803002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1263803002/1

[commit-bot: I haz the power, 2015-07-30 12:05:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-30 12:06:23]

Patchset 1 (id:??) landed as
https://crrev.com/1f79b119adb1926e21be8959c283b66a25c91fc1
Cr-Commit-Position: refs/heads/master@{#341101}